1. Field of the Invention
The present invention pertains to optical display devices that produce spatial objects, i.e., natural appearing objects that float in space and three-dimensional (3-D) objects and, more specifically, pertains to a spatial object display that combines a background image or image plane with multiple foreground spatial objects.
2. Description of Related Art
Optical display devices that image an object seemingly floating in space have been well known since at least the turn of this century. The two most common methods of producing floating objects has been by either reflecting an object from one or more curved mirrors (i.e., parabolic) or viewing an object properly positioned behind one or more lenses. These methodologies are termed reflective or transmissive spatial object devices, respectively. In recent decades there has been a focus on improving particular aspects of these well-known illusions. Recently there has been interest in providing a background image to appear behind the spatial objects.
One means of providing a background image spatial object display is taught by Monroe (U.S. Pat. No. 5,257,130). In this disclosure a scrim is used to permit a spatial object (produced by either reflective or transmissive means) to appear in front of the scrim (the optical rays forming the object having passed through the open mesh weave of the scrim), while the scrim simultaneously serves as a front projection screen surface on which the background image can be projected. As seen in Prior Art FIG. 1, this device comprises a reflective spatial object display with a first concave mirror 8 and a second concave mirror 10. A reflective display 2 produces reflective spatial object image 4 which, when reflected, produces reflected spatial object 6. A scrim 14 allows the reflected spatial object 6 to pass through, but also serves as a front projection screen for displaying images from projector 12. This device is generally limited to low ambient light environments because of the tendency for bright light to wash out the image projected on the scrim 14. Further, the projector is ideally positioned in the approximate area occupied by the observers. These limitations renders the device unusable in most advertising and presentational environments such as a store front window. Also, the brightness and sharpness of the spatial object is reduced because it must be viewed through the light-absorbing scrim. Furthermore, the scrim does not allow enhanced depth to its front projected imagery.
Warren et al. (U.S. Pat. No. 5,311,357) discloses the use of two concave mirrors to produce a spatial object with one of the concave mirrors being partially transparent. Behind this partially transparent mirror is an image display which can be readily seen by an observer through the partially transparent concave mirror. As shown in Prior Art FIG. 2, the device uses a reflective real spatial object 26 created from an actual object 20 which is illuminated by a light 20 shielded by a shield 30. Here one of the concave mirrors is a partially transparent concave mirror 24 which allows an observer to view a background large screen display 28.
Although this device does provide a spatial object floating before a background image, it suffers from several disadvantages. First, the partially transparent concave mirror is an excessively expensive custom optical component. Second, the curve of the partially transparent concave mirror visibly distorts the background image. Third, the background image, on a large screen display, is positioned far back into the device, creating the awkward necessity of peering into a black box. Finally, this device does not provide a means to enhance the 3-D appearance of the background image so that the background image always appears flat. If the background image were to appear to have depth, the appearance of spatial object would be complemented resulting in high impact presentations.
Still another background image spatial object display is taught by Noble (U.S. Pat. No. 4,671,625). This transmissive spatial object display utilizes a combination of convex lenses with improved viewing of the spatial object provided by a visible reference around the area in which the spatial object appears to serve as a visual cue for the observer. This visible reference is taught primarily as the edge of a box (i.e., shroud) that extends out from the closest convex lens to the observer. A background image is provided by reflecting the spatial object off a partially transparent mirror with the image behind in an optical arrangement similar to Warren, except that this partially transparent mirror is flat and is not used to create the spatial object.
This device is illustrated in Prior Art FIG. 3, where a transmissive spatial object 46 created by a transmissive spatial object image 44 is produced on a transmissive spatial object display (i.e., CRT) 42. A first convex lens 50 and a second convex lens 48 manipulate the light rays to produce the transmissive spatial object 46. The transmissive spatial object 46 is viewed from as the reflection of a partially transparent mirror 52. This mirror 52 folds the beam of the transmissive spatial object 46 and allows a background image 52 (i.e., a poster or full motion display) to appear behind the partially transparent mirror 52. The edges 56 of an aperture in a housing 40 serve as a "visible reference" forming a transparent plane 57 that enables the observer to comprehend the spatial position of the transmissive spatial object 46.
As a result, the transmissive spatial object 46 appears to float within the housing 40 and does not protrude beyond the visible reference of the housing opening edges 56, where it would create a much greater visual impact. This device also suffers from the same drawback as Warren in that the observer must peer into a box to observe the background image. This problem is exacerbated by the addition of the box extension which projects out to the point in space where the spatial object appears so that the box edge can serve as the "visible reference." This visible reference operates in conjunction with an optional second visible reference (not shown) located near the convex lens to assist the viewer in accurately aligning the object in space. Unfortunately, peering deep into this box to view the image is somewhat unnatural and may be an irritant to observers accustomed to interacting directly with a television screen or a computer monitor. Also, by recessing the image deep within a box, only a single observer at a time can peer into the box to view the image. As a result, this device is unable to communicate simultaneously with multiple observers. The disclosure also fails to teach a method for providing a unique 3-D appearance to the background image that can complement the 3-D appearance of the spatial object.
Noble also discloses the combining of two spatial objects by aligning two full sets of convex lens (4 lenses in total) with a single partially transparent mirror. Prior art FIG. 4 illustrates the same device of FIG. 3, except that the background image is replaced with a second transmissive spatial object optical arrangement. This arrangement consists of a second transmissive spatial object display 60 imaging a second transmissive spatial object image 62, with a third convex lens 66 and a fourth convex lens 68 separated by a fully reflective mirror 70 producing a second transmissive spatial object 64. It is important to note that the first convex lens 50 and the second convex lens 48 are positioned closer together to ensure the transmissive spatial object 46 remains inside the housing 40. This device suffers from the fact that both transmissive spatial objects 64 and 46 are contained inside the housing 40, at or behind the "visible reference" housing opening edges 56, rather than preferably extending beyond the housing 40 for dramatic spatial object effects.
Noble does not, however, teach how to provide a background image behind these two spatial objects, nor does he offer a method of reducing the bulk of the display necessitated by two full sets of optics. Nor does he teach a method for reducing reflections on the first convex lens, other than the shroud. Also, the configuration he teaches requires both spatial objects to be contained within the box behind the edges of the box forming the transparent plane of the visible reference means. Noble does teach that the most important application of his invention is for the spatial object to optically interact with the background image or with an additional spatial object. Such interaction requires multilayered coordinated video production techniques that are well known in the art and are commonly used for creating special effects in motion pictures in the form of multilayer Pepper's ghost images.
Finally, it is well known in the art and pertinent to this application that the Pepper's ghost illusion can produce a floating object. Typically a real object is reflected by a partially-reflective mirror that also allows a background scene to show through. From the perspective of a viewer, the mirror is invisible and the reflected image appears as a transparent "ghost" superimposed over the background scene. If the reflected object is three-dimensional, the superimposed image will also appear three-dimensional. If the image source is a two-dimensional display, the superimposed image will appear flat.
Over the years many special effect technicians have produced motion picture and video effects involving real objects with the addition of high contrast lighting, shiny surfaces, etc. to enhance the three-dimensional appearance of the superimposed image. Similar "dimensionalizing" techniques have been applied in computer animations in the form of "rendering" software. Yet, despite all these efforts, when the display source is two-dimensional, such as a CRT, even the best object productions appear flat when reflected by a partially reflective mirror. Further, when the semireflective mirror is used in a display device, an observer can readily discern the perimeter of the mirror and readily realizes that the "floating object" is merely a simple trick reflection.